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Alternate Wnt Pathway

Abstract

A canonical Wnt pathway has been established in which Wnt proteins signal though homologues of b-catenin, which regulates activity of Tcf transcription factors (see the Wnt/beta-catenin Connections Map by Moon). Herman analyzed Wnt signaling in C elegans (see the C. elegans Wnt/beta-catenin Connections Map by Bowerman) that controls the fate of developing tail cells. As is typical, signaling in these cells began with homologues of Wnt and its receptor and ended with the TCF homologue POP-1. However RNA-mediated interference with any or all of the three worm homologues of b-catenin had no effect on the polarity of the tail cells. Since more than 99% of the C elegans genome has been sequenced, it appears unlikely that there are other b-catenin-like proteins that could compensate. Herman, thus, concludes that tail cell fate is modulated by a Wnt pathway with components distinct from those in the canonical pathway. Identification of the remaining components in the pathway should provide new insight into how variations in Wnt signaling allow for control of multiple cell types during development.